1. Field
The present disclosure relates to a method for producing a saturated hydrocarbon fuel that may be used as diesel and aerial oil by subjecting a biomass containing benzyl phenyl ether to isomerization and hydrodeoxygenation using an acid-metal composite catalyst. More particularly, the present disclosure relates to a method for producing a high-carbon number saturated hydrocarbon fuel by isomerizing the oxygen present in benzyl phenyl ether derived from lignin as a biomass into an aromatic alcohol, while inhibiting decomposition of a carbon compound.
2. Description of the Related Art
Lignocellulosic biomass occupying 95% or more of the total vegetable biomasses includes cellulose (40-60%), hemicellulose (20-40%) and lignin (10-25%). Cellulose and hemicellulose have been studied intensively about production of bioethanol through saccharification and fermentation processes. However, lignin forms a natural polymer structure of complicated phenolic compounds to serve to protect vegetable cells from external biological attacks, and thus forms a rigid cellular wall.
Since it is difficult to decompose lignin as mentioned above, it is frequently discarded, or it largely depends on a thermal decomposition process requiring high energy consumption using high temperature and pressure, if it may be utilized as a fuel or chemical product. In brief, there are only insufficient technological processes for converting lignin into an energy source capable of substituting for the existing petrochemicals. Bio-oil obtained through thermal decomposition of lignin has a large amount of water and oxygen functional groups, and thus is problematic in that it easily causes corrosion of metals, or the like. Therefore, such bio-oil has many potential problems in terms of corrosion of engines when used as a fuel for vehicles.
Accordingly, there is an imminent need for developing a process for converting lignin efficiently into one that may be used as a high-energy source. Benzyl phenyl ether is a typical compound derived from lignin and includes two benzene rings and ether bond, so that it represents characteristics of lignin decomposition materials. Conversion of benzyl phenyl ether may be applied to conversion of other lignin-derived compounds.
Use of lignin as a biofuel is intended to minimize the number of oxygen functional groups present in lignin, and thus to minimize thermal and chemical unstability of biofuel, thereby providing a high-efficiency energy source. In addition, a particular process thereof includes an indirect hydrodeoxygenation process in which hydrodeoxygenation is accomplished while maintaining a high carbon number of starting materials through isomerization, instead of cleavage of an ether functional group that is a kind of oxygen functional group present in high-molecular weight lignin structure to produce low-molecular weight carbon compounds.
The present inventors have developed a two-step process including: isomerization of lignin dimer having an ether functional group ((CnHm)—O—(CxHy)) for conversion into an optimized biofuel having highly efficient quality; and hydrodeoxygenation. We also have developed an optimized acid catalyst for the isomerization and an optimized composite of metal nanoparticles with an acid catalyst for the hydrodeoxygenation.